Development of N-in-P Silicon Strip and Pixel sensors for very high radiation environments Y. Unno For the Collaboration of KEK, Univ. Tsukuba and Hamamatsu Photonics K.K. 1Y. Unno, 5th "Trento" Workshop, Manchester, UK, Feb., 2010

R&D of P-type Silicon Sensor We have been developing a silicon microstrip sensor using 6-inch (150 mm dia.) p-type material – in ATLAS experiment Has fabricated n-in-p 1 cm x 1 cm (miniature) and 9.75 cm x 9.75 cm (main) sensors with Hamamatsu Photonics K.K. (HPK) Results were reported recently in the 7th International “Hiroshima” Symposium…, Hiroshima, 28 Aug. – 1 Sep. 2009, and in this conference, “Surface effect…” by H. Sadrozinski, etc. Achievements, e.g. – Operation up to 1 kV – Radiation damage tested by protons and neutrons up to ~ MeV-neutron equivalent/cm 2 and new results from the R&D wafer by the collaboration in Japan… Y. Unno, 5th "Trento" Workshop, Manchester, UK, Feb., 20102

New R&D Wafer PTP study – Strips mini – Slim edge study – Diodes – 1-20 Guard ring study – Diodes – HPK 6 inch (150 mm) wafers, p-type and n-type Y. Unno, 5th "Trento" Workshop, Manchester, UK, Feb., Pixel (1-29) 10.5 mm x 10 mm Strips (30-89) 10 mm x 10 mm Diodes (1-32) 4mm x 4mm

Punch-Through Protection Structure TCAD simulation – P-stop case: 4x10 12 ions/cm 2 N-N gap: 20 µm – P-spray case: 2x10 12 ions/cm 2 N-N gap: 12 µm – Interface charge: positive 0.5x10 12 or 1x10 12 Y. Unno, 5th "Trento" Workshop, Manchester, UK, Feb., PT voltages – P-stop without Al-extension (P6 20 um) – P-stop with Al-extension (P6 HX2) – P-stop with Al-extension and enhanced interface charge (P6 HX2 1e12) – P-spray (R 12 um)

New PTP Fabrication Bias ring Al extension BZ4B, BZ4C – 1: Up to p-stop – 2: No extension – 3: Over p-stop – 4: Full extension BZ4D – 1: No p-stop – 2: Up to p-stop – 3: No extension – 4: Over p-stop – 5: Full extension Y. Unno, 5th "Trento" Workshop, Manchester, UK, Feb., 20105

PT Onset Voltages - Measurements Pre-irradiation, P-stop 4x10 12 Distinct groups – With/Without extension – Full extension is the sharpest turn-on Comparison – ATLAS07 S2R2 wafer (P-spray 2x10 12 ) – BZ1 (NN gap= 12µm), Others (NN gap=20 µm) – No difference in onset voltage – Difference in sharpness Y. Unno, 5th "Trento" Workshop, Manchester, UK, Feb., BZ4D-5 BZ4B-2 BZ4C-2 BZ4D-3 BZ4D-1 BZ4D-2, BZ4C-4

I-V and Onset of Microdischarge New PTP fabrication – 1 cm x 1 cm miniature sensors No onset of microdischarge up to 1,000 V 4 wafers fabricated – Left figure is those on one wafer of the four Looking forward to irradiation with protons, neutrons, and gammas Y. Unno, 5th "Trento" Workshop, Manchester, UK, Feb., 20107

Slim Edge Study A goal – ATLAS Insertable B- Layer (IBL) 2x1 Planar Pixel Sensor Envelope – Active pixel-dicing edge: 0.45 mm In one of the edge, the distance is varied in diodes Y. Unno, 5th "Trento" Workshop, Manchester, UK, Feb., 20108

Slim edge - Measurements Results are of N-type wafer – Layout for P-type wafers is found to be defective – Layout for N-type wafer is correct Thickness (as is, thinned) – 320 (W5), 200 (W7,13) µm Edge implantation – N+ or P+ Y. Unno, 5th "Trento" Workshop, Manchester, UK, Feb., N-sub/N-edge N-sub/P-edge N-sub P+ N+ N+ GR Edge N-sub P+ P+ P+ GR Edge

Slim Edge - Measurement Square root of V_bias is linearly dependent on the edge distance – Reflecting the depletion along the surface Distance can be ≤500 µm for the bias voltage up to 1 kV – (Almost) No safety margin for a thickness of 320 µm – More than a factor of 2 safety margin for a thickness of µm Note: – N-type, FDV ~70 V – P-type, when FDV ~200 V, 40% less distance may be required – After irradiation, N-type ~ P-type FDV, though. Y. Unno, 5th "Trento" Workshop, Manchester, UK, Feb.,

Guard Ring Study In order to investigate whether the number of guard rings will help to reduce the edge distance – Variation up to 3 guard rings Note the width of guard rings – Width of Edge-Edge of guard rings are – 1GR-L = 2GR-N – 1GR-M = 2GR-O = 3GR-P Y. Unno, 5th "Trento" Workshop, Manchester, UK, Feb., STD-K1GR-L1GR-M 2GR-N 2GR-O 3GR-P

Guard Ring Study Tested with N-sub wafer I-V measurement – N-edge could hold 1 kV – P-edge for investigation Systematic onset of leakage current was observed – The best is 2GR-O, i.e., wide- spread 2 guard ring, but… – What is the meaning of the results? Y. Unno, 5th "Trento" Workshop, Manchester, UK, Feb.,

Guard Ring Study Horizontal axis: total width of fields without implantation Vertical axis: square root of bias voltage Linear dependence, reflecting the depletion along the surface No difference in the variations of the guard ring Y. Unno, 5th "Trento" Workshop, Manchester, UK, Feb.,

Thinned Pixel Sensors Wafer thickness – P-type: 320 µm – N-type: thinned to 200 µm 150 µm possible Excellent I-V performance – ≤1,000 V – Both in the p-type and n-type Y. Unno, 5th "Trento" Workshop, Manchester, UK, Feb., One of FE-I3 pixel sensor P-type wafer example

New FE-I4 Pixel Sensors HPK 2x1 FE-I4 sensor complying with the "IBL 2-chip planar sensor tile, Rev ", 18.8 mm x 41.3 mm, with the edge space in the longitudinal pixel direction of mm 3 types of isolation (p-stop (common, individual), p-spray) x 1 type of bias (PT) x 2 sensors/type/wafer Normal thickness (320 um) and Thinned (150 um) wafers Others are single-chip FE-I4, single-chip FE-I3 (3 types of isolation x 2 types of bias (PT, PolySi)), 2x2 FE-I3 sensors (3 types of isolation x PT), etc. To be fabricated – Normal thickness: June 2010 – Thinned: July 2010 Y. Unno, 5th "Trento" Workshop, Manchester, UK, Feb., Single-chip FE-I3 etc. 2x1 FE-I4 2x2 FE-I3

Summary We have shown – PTP onset voltage, sharpness, limiting resistivity are improved by the new structure with the extended electrode covering the PT gap – The width of the edge can be ≤500 µm (in the N-type wafer, at the moment; P-type to be soon) – No fundamental difference in the number of guard rings in order to reduce the width of the edge better to have a less implant area and a wider non-implant field, thus to have a narrower total edge width for the same bias voltage – Thinned sensors, 200 µm thick, hold 1,000 V Looking forward to the performance after irradiation Y. Unno, 5th "Trento" Workshop, Manchester, UK, Feb.,